Melatonin may be able to protect corneal epithelial cells and, in turn, could be used as a potential treatment for dry eye, researchers from China suggest.

Their study, presented as an online abstract as part of ARVO’s 2020 meeting, reports melatonin significantly protected human cell viability and decreased apoptosis in corneal epithelial cells exposed to hydrogen peroxide. Additionally, the researchers observed significant improvements in clinical parameters and increased tear volume after intraperitoneal injection of melatonin in a dry eye mouse model.

The research paper suggests melatonin protects human corneal epithelial cells against oxidative damage by trigging hemeoxygenase-1 expression, which helps maintain normal autophagy.

In the study, mice were injected with scopolamine (0.5mg/0.2mL) three times a day and were exposed to a dry environment with humidity less than 30% for seven consecutive days. In addition, primary human corneal epithelial cells and a HCE cell line were exposed to hydrogen peroxide.

The investigators found melatonin significantly protected cell viability and decreased apoptosis in the human corneal epithelial cells exposed to hydrogen peroxide, and the intraperitoneal injection of melatonin in the dry eye mouse model also showed significant improvements.

Melatonin was able to reduce intracellular reactive oxygen species (ROS) production and maintain mitochondrial function by activating hemeoxygenase-1 (HO1). SnPP, a HO1 inhibitor, largely diminished the protective effects of melatonin, the researchers noted. Moreover, autophagic flux was impaired in dry eye, which could be reversed by melatonin.

This study may provide a potential treatment choice for dry eye disease in the future, the investigators note.